The present application relates generally to multimode seekers, and in particular to an algorithm for detecting and tracking laser pulses.
Seeker guided ordinances may be launched or dropped some distance away from a target, then guided to the target, saving a delivery vehicle from having to travel into the area of the target. Seekers perform target detection and tracking by sensing energy such as sound, radio frequency, infrared, or visible energy that targets emit or reflect. Seeker systems that detect and process one type of energy are known generally as single-mode seekers, while seeker systems that detect and process multiples types of energy are generally known as multimode seekers.
Seeker homing techniques can be classified as active, semi-active, and passive. In active seekers, a target is illuminated and tracked by equipment onboard the ordnance itself. A semi-active seeker is one that detects and follows a target by tracking energy from an external source, separate from the ordnance, and reflected by the target. The illuminating source can be ground-based or airborne. Semi-active and active seekers require the target to be continuously illuminated until target impact. Passive seekers use external, uncontrolled energy sources such as solar light or target emitted heat. Because semi-active seekers involve a separate, external source, this source can also be used to “designate” the correct target. In this scenario, the ordnance “acquires” and “tracks” the designated target.
In semi-active laser (SAL) seeker guidance systems, an operator points a laser designator at the target, and the laser radiation bounces off the target and scatters in multiple directions. The laser designator may emit the laser at a predetermined pulse repetition frequency (PRF) so that a seeker system is able to identify the reflected laser. When the ordnance is close enough for some of the reflected laser energy from the target to reach the ordnance's field of view (FOV), a seeker system of the ordnance detects and identifies the laser energy. The seeker determines that the detected laser energy has the PRF assigned by the designator and determines the direction from which the energy is being reflected. This allows the ordnance to guide itself accurately to the target. It is desirable to optimize the laser acquisition process in order to improve the overall functionality and maneuverability of the seeker system.